This invention relates to a self-aligning pulley and an engine accessory belt drive incorporating such a pulley.
It is known in the art to use pulleys and belts to drive automotive engine accessories such as alternators, air conditioning compressors, power steering pumps, and the like. Proper alignment of these pulleys and belts is necessary for the quiet operation of the belt drive. Typically, in volume production, the accessories are all mounted on brackets that have tolerances which can cause misalignment. Short belt spans are more critical than long spans because the belts lack flexibility over short spans to compensate for any misalignment of the pulleys.
The present invention provides a self-aligning pulley assembly for use in a tensioned belt drive, wherein the pulley may need alignment.
The present invention also provides an engine accessory belt drive which has a self aligning pulley assembly to correct pulley to belt misalignment in the belt drive.
In a preferred embodiment, a self-aligning pulley assembly according to the invention includes a relatively stationary outer assembly and a universally pivotable inner assembly supported by the outer assembly.
The inner assembly includes a pulley for engaging a generally flat belt, a bearing rotatably supporting the pulley on a rotational axis, and support members having convex part-spherical outer surfaces, and inner portions engaging and supporting the bearing.
The outer assembly includes a relatively stationary support, guide members carried by the support and having recessed surfaces engagable with the spherical outer surfaces of the support members, an axle defining a relatively fixed support axis and extending through the guide members and the inner assembly, and a fastener associated with the axle and adjustable between loose and tight positions for, respectively, movably or fixedly holding the recessed surfaces of the guide members against the spherical surfaces of the support members;
During self-alignment of the pulley with a belt, the fastener is maintained in the loose position, allowing limited universal pivoting of the rotational axis of the pulley to self-align the pulley with the direction of motion and tilt of the belt surface. After the pulley is aligned, the fastener is tightened (moved to the tight position) to fix the rotational axis of the pulley and the inner assembly in the aligned position of the pulley.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.